The present invention relates to a solder jet machine for soldering electronic parts already mounted on a substrate with their leads inserted thereinto by receiving a substrate subject to soldering carried in from its substrate-carrying-in side and ejecting molten solder from its solder ejecting ports to the pattern side of the substrate subject to soldering while conveying the substrate subject to soldering keeping a pattern side facing down and to a method of soldering used in the above machine.
Solder jet machines are already known for soldering surface mount devices and discrete parts (parts having lead legs) mounted on a substrate in a mixed state by supplying the substrate subject to soldering with molten solder ejected from their jet nozzles while conveying the substrate subject to soldering.
Solder jet machines of this type includes a first jet nozzle 1 for satisfactorily supplying molten solder to a substrate P subject to soldering on which electronic parts have been mounted and a second jet nozzle 2 for removing excess molten solder from the substrate P subject to soldering to which solder has been already supplied, as shown in FIGS. 7 and 8.
In the above solder jet machine, the first jet nozzle 1 and the second jet nozzle 2 are connected to a duct 3 for the first nozzle and a duct 4 for the second nozzle, respectively, and both of the ducts are soaked in a solder bath 5 in which molten solder is stored.
This solder jet machine is configured by ejecting molten solder from the first jet nozzle 1 and the second jet nozzle 2 toward a path 10 for conveying a substrate subject to soldering by rotationally driving jet impellers 6 and 7 arranged to face each of the openings at one end of the duct 3 and at one end of the duct 4, respectively.
On the upper end portion of the first jet nozzle 1 mounted is a solder wave forming plate 9 having multiple solder ejecting ports 8 provided thereon. As shown in FIGS. 9a and 9b, the ejecting ports 8 are designed to have the same bore diameter and the same round shape and they form three rows relative to a direction A in which the substrate P subject to soldering is conveyed: a first ejecting-port row 8A, a second ejecting-port row 8B and a third ejecting-port row 8C. In this solder jet machine, the wall portion surrounding each solder ejecting port 8 on the solder wave forming plate 9 is flat.
The substrate P subject to soldering have warps of various sizes caused therein when it is heated by molten solder. And in the solder jet machine of the prior art which has the above-described configuration, when the height of the pile of the molten solder ejected from the solder ejecting ports 8A is low, there are produced some places in the pattern side of the substrate P subject to soldering and in the portions of electronic parts subject to soldering which molten solder does not touch, which means causing non-wetting.
As one of the prior art methods to deal with the problem of non-wetting, it is possible to heighten the pile of the molten solder by increasing the rpm of the jet impellers 6 and 7. However, at the time of increasing the rpm of the jet impellers 6 and 7, the average height of the pile of the molten solder over a time is increased, but on the other hand, the height varies with time and is likely to be unstable. And when the height of the pile of the molten solder ejected from the solder ejecting ports 8 becomes low temporarily, there may be produced some places in the pattern side of the substrate P subject to soldering and in the portions of electronic parts subject to soldering which the molten solder does not touch, which means causing non-wetting in some parts.
Alternatively, it is possible to provide a configuration which enables heightening the pile of the molten solder without increasing the rpm of the jet impellers 6 and 7 by forming each solder ejecting port 8 on the solder wave forming plate 9 in such a manner as to be allowed to project from the surface of the solder wave forming plate 9 by coining, as shown in FIGS. 10 and 11.
However, although the pile of the molten solder can be heightened without increasing the rpm of the jet impellers 6 and 7, there still arises a problem that a satisfactorily stable height of molten solder wave cannot be obtained only by forming each solder ejecting port 8 in such a manner as to be allowed to project upwardly. Specifically, the wave of the molten solder ejected from the first ejecting-port row 8A is disturbed by the molten solder ejected from the third and the second ejecting-port rows 8C and 8B and becomes unstable, which causes the soldering defect that permits the molten solder to run onto the component side of the substrate P subject to soldering which has been carried in the solder jet machine.
Accordingly, the object of the present invention is to provide a solder jet machine and a method for soldering which enable obtaining a molten solder wave of stable height.
In order to attain the above object, the solder jet machines according to the present invention is characterized by: forming a wall portion surrounding each solder ejecting port in such a manner as to be allowed to project upwardly from the surface of the solder wave forming plate; and forming a groove portion on the surface of the solder wave forming plate around each solder ejecting port for introducing the ejected molten solder in such a direction as to be allowed to flow down.
And the method of soldering according to the present invention is characterized by: forming a wall portion surrounding each of the solder ejecting ports formed in multiple rows relative to the direction in which a substrate subject to soldering is conveyed, in such a manner as to be allowed to project upwardly from the surface of the solder wave forming plate; forming a stable solder wave by allowing the molten solder ejected from the solder ejecting ports on the downstream side relative to the substrate-conveying direction to flow down between the adjacent solder ejecting ports on the upstream side relative to the substrate-conveying direction and by introducing the molten solder ejected from the above solder ejecting ports in such a direction as to be allowed to flow down via groove portions formed around the above solder ejecting ports; and soldering the substrate subject to soldering using the above wave.
A solder jet machine according to the first aspect of the invention as set forth in claims is characterized by: forming the above-described solder ejecting ports in multiple rows relative to the direction in which the substrate subject to soldering is conveyed; forming the above-described solder ejecting ports in such a manner that an imaginary line which links a solder ejecting port in the row on the upstream side relative to the substrate-conveying direction and a solder ejecting port in the row on the downstream side relative to the substrate-conveying direction is sloped so that the molten solder ejected from the solder ejecting ports on the upstream side can flow down between the adjacent solder ejecting ports on the upstream side; and forming groove portions on the surface of the solder wave forming plate around at least part of the above-described solder ejecting ports for introducing the ejected molten solder in such a direction as to be allowed to flow down.
A solder jet machine according to the second aspect of the invention is characterized by: forming solder ejecting ports on the solder wave forming plate in three rows: a first electing-port row, a second electing-port row and a third ejecting-port row, in this order, from the upstream side to the downstream side relative to the direction in which a substrate subject to soldering is conveyed; configuring the solder ejecting ports and the solder wave forming plate in such a manner that at least part of the molten solder ejected from the solder ejecting ports in the third row flows down between the adjacent solder ejecting ports in the second ejecting-port row and between the adjacent solder ejecting ports in the first ejecting-port row; and forming groove portions around the solder ejecting ports in the second ejecting-port row for introducing the molten solder ejected from the solder ejecting ports in both the second and the third ejecting-port rows between the adjacent solder ejecting ports in the first electing-port row.
A solder jet machine according to the third aspect of the invention is characterized by: forming solder ejecting ports on the solder wave forming plate in three rows: a first electing-port row, a second electing-port row and a third ejecting-port row, in this order, from the upstream side to the downstream side relative to the direction in which a substrate subject to soldering is conveyed; forming groove portions around the solder ejecting ports in the first, the second and the third ejecting-port rows; and forming groove portions from the groove portions around the solder ejecting ports in the first ejecting-port row toward the upstream side on the solder wave forming plate relative to the direction in which the substrate subject to soldering is conveyed, and linking the groove portions 33 to each other.
In the above-described solder jet machines, the wall portion surrounding each solder ejecting port on the solder wave forming plate is allowed to project upwardly and the groove portions for introducing the ejected molten solder in such a direction as to be allowed to flow down are formed on the surface of the solder wave forming plate around at least part of the above-described solder ejecting ports; therefore, according to the solder jet machines, it is possible to heighten the pile of the molten solder without increasing the rpm of the jet impellers, to obtain molten solder waves of satisfactorily high from the solder ejecting ports projecting from the surface of the solder wave forming plate, and hence to realize a satisfactory soldering performance.
The method of soldering as set forth in claims carries out soldering in such a manner as to supply molten solder to a substrate subject to soldering by ejecting the molten solder from multiple solder ejecting ports formed on a solder wave forming plate during the conveyance of the substrate subject to soldering, characterized by: forming a wall portion surrounding each of the above-described solder ejecting ports formed in multiple rows relative to the direction in which the substrate subject to soldering is conveyed in such a manner as to be allowed to project upwardly from the surface of the solder wave forming plate; arranging the solder ejecting ports in such a manner that an imaginary line linking a solder ejecting port in the row on the upstream side and a solder ejecting port in the row on the downstream side is sloped upward in the direction in which the substrate subject to soldering is conveyed, so that the molten solder ejected from the solder ejecting ports on the downstream side can flow down between the adjacent solder ejecting ports on the upstream side; promptly introducing the molten solder ejected from the above-described solder ejecting ports in such a direction as to be allowed to flow down via the groove portions formed around at least part of the above-described solder ejecting ports so as to stabilize the solder wave; and soldering the substrate subject to soldering using the solder wave ejected from the above-described multiple solder ejecting ports.
According to this soldering method, the wall portion surrounding each of the solder ejecting ports formed in multiple rows relative to the direction in which a substrate subject to soldering is conveyed is formed in such a manner as to be allowed to project upwardly from the surface of the solder wave forming plate, the molten solder ejected from the solder ejecting ports on the downstream side is allowed to flow down between the adjacent solder ejecting ports on the upstream side, and the molten solder ejected from the above-described solder ejecting ports is promptly introduced in such a direction as to be allowed to flow down via the groove portions formed around the above-described solder ejecting ports so that solder waves of high stability and large height can be formed; thus, with these solder waves, it becomes possible to solder the substrate subject to soldering satisfactorily.